Seems like this isn't considered to be a big issue, beyond that it is a very visible thing that instinctively 'feels' like a bad idea.
> Rocket engines spray water (H2O) and carbon dioxide (CO2) into the ionosphere, quenching local ionization by as much as 70%. A complicated series of charge exchange reactions between oxygen ions (O+) and molecules from the rocket exhaust produce photons at a wavelength of 6300 Å–the same color as red auroras.
> Once rare, ionospheric “punch holes” are increasingly common with record numbers of rocket launches led by SpaceX sending Starlink satellites to low-Earth orbit. Ham radio operators may notice them... These effects may be troublesome, but they are shortlived; re-ionization occurs as soon as the sun comes up again.
> Rocket engines spray water (H2O) and carbon dioxide (CO2) into the ionosphere, quenching local ionization by as much as 70%. A complicated series of charge exchange reactions between oxygen ions (O+) and molecules from the rocket exhaust produce photons at a wavelength of 6300 Å–the same color as red auroras.
> Once rare, ionospheric “punch holes” are increasingly common with record numbers of rocket launches led by SpaceX sending Starlink satellites to low-Earth orbit. Ham radio operators may notice them... These effects may be troublesome, but they are shortlived; re-ionization occurs as soon as the sun comes up again.